1. Field of the Invention
The present invention relates to a hard disc drive in which vibration of a slider due to a flow of air caused when a disc rotates may be effectively reduced.
2. Description of the Related Art
FIG. 1 is a cross-sectional view of a general single-channel type hard disc drive that drives a single disc or a single head. Referring to FIG. 1, the hard disc drive includes a disc 1 having a recording surface on which information is recorded, and a head gimbal assembly (HGA) 2.
The disc 1 is rotated by a spindle motor 4 installed on a base 3. The HGA 2 includes a slider (not shown) having a magnetic head to write data on and to read data from the recording surface of the disc 1. The HGA 2 is combined with a suspension 7 that is combined with an actuator 6 that is driven by a voice coil motor 5 to rotate with respect to a pivot bearing 6a. The structure of the HGA 2 is well known in the field of disc recording/reproducing apparatuses, and therefore its detailed description will be omitted here.
The recording surface of the disc 1 faces the base 3, and the HGA 2 is positioned between the base 3 and the disc 1 and moves along the recording surface of the disc 1. As shown in FIG. 2, a space for the disc 1 and the aforementioned related elements is encompassed by a frame 3a. The frame 3a is closely adhered with a lid (not shown) that seals the space. A ramp 3b is provided very close to the recording surface of the disc 1 at a bottom of the base 3, so as to provide an air damping region of the disc 1. A slider moving region 3c is a place where the HGA 2 and the suspension 7, which holds the HGA 2, move. The slider moving region 3c is lower than the ramp 3b. Also, a recession 4b is provided at a flange 4a of the spindle motor 4 to be level with the slider moving region 3c. The recession 4b allows the suspension 7 to move within the slider moving region 3c. In conclusion, the ramp 3b is lower than the flange 4a and the slider moving region 3c is lower than the ramp 3b. Also, a distance between the disc 1 and the base 3 is set to be very narrow, except at the slider moving region 3c. 
In the hard disc drive, the disc 1 rotates within a space defined by the base 3 and the lid which is put on the base 3 to close the space. The rotation of the disc 1 enables air to flow along the shape of the space provided in the hard disc drive. The rotation of the disc 1 results in a flow of air in the hard disc drive, and then, the flow of air causes the HGA 2 to rise to an equilibrium position where a rising force from the flow of air is equal and opposite to a preload (or gramload) applied to the head. A head suspension assembly (HSA), which includes the HGA 2 and the suspension 7, vibrates due to the flow of air caused by the rotation of the disc 1. That is, the suspension 7 and the HGA 2, which is attached to a front of the suspension 7, vibrate due to the flow of air in the hard disc drive. The suspension 7 and the HGA 2 vibrate with a particular bandwidth of frequency, generally around 10 KHz.
In general, the HSA is set to apply a preload to the slider so that the slider has a rising height (Z-height) in accordance with the rotation speed. However, if excessive or insufficient preload is applied to the slider or the slider is abnormally positioned in the HGA 2, the suspension 7 and the HGA 2 locally vibrate to a large degree at a particular frequency bandwidth, e.g., 10 KHz. The local vibration deteriorates a position error signal (PES), and as a result, causes errors. For instance, when the slider (more specifically, a reading element or a writing element included in the slider) performs reading/writing operations at a target track, the vibration may cause the slider to read data from or write data to an adjacent track, not the target track, thereby deteriorating performance of the hard disc drive, as well as the servo characteristics of the hard disc drive.